Prosecutors have dropped the case against a student arrested for holding a banner showing David Cameron , Ed Miliband, Nick Clegg and Nigel Farage above the slogan “All F******g W*****s”.

Adam Barr, a student at the London School of Oriential and African Studies (Soas), was due to attend court on Friday charged with holding an offensive protest banner under section five of the 1986 Public Order Act.

He was arrested last April after a primary school teacher complained about him holding the banner at a protest in east London against developers who build so-called poor doors for social tenants in luxury city apartments.

This is where wealthy and housing association tenants enter through separate doors.

But last week, the Crown Prosecution Service told Barr, 24, it would no longer pursue the case due to lack of evidence.

Barr told the Guardian an officer had told him the banner was a breach of the Public Order Act and that he had received a complaint.

His companions dropped it but he kept hold of it because he did not think it was illegal.

He said: "I was making a political point. It may have been crude, but it was also meant to be humorous. It was about not respecting people in authority just because they get elected in a bent and corrupt system.

Protest: The student had the banner at a protest event against poor doors like this (Image: Roy Fisher)

“The officer did a weird teacher-like thing: he gave me a minute to consider. He was relatively polite then he came back and arrested me. I was put in a van and taken off to Bethnal Green police station for four hours.”

Barr refused to accept a £90 penalty notice and insisted on being summoned to court where he pleaded not guilty.

In the course of the case, Barr was told Tower Hamlets police had inadvertently destroyed the banner.

The complainant told officers she feared pupils in her class might repeat the words if they saw them.

Barr said he was relieved the case has been discontinued.

He added “It’s amazing it got so far without someone at the CPS realising it breached my freedom of speech.”

The case echoed another in 2010, when officers from the same Metropolitan police division launched and dropped a similar prosecution.